Heretofore, a film has been required, which can be suitably used for efficiently covering a protected surface or a surface that needs to be protected.
For example, a surface protection film is proposed, which has weak pressure dependency at the time of adhering, being able to easily adhered (temporarily adhere) to the surface of various materials (objects to be protected) such as metal plate etc. even when the film is pressed with a low pressure, and also showing excellent peelability after the use (for example, Japanese Provisional Patent Publication No. 2001-139898).
In another example, a transparent, electrically conductive and heat sealable material and a carrier tape lid using the same are proposed, which show no lowering in antistatic property even at a low humidity, and have such transparency that contents in the tape lid can be visually recognized (for example, Japanese Provisional Patent Publication No. 2001-348561).
In still another example, a surface protection material is proposed, which has a pressure sensitive adhesive layer on a substrate, showing good initial adhesiveness, small change in adhesive force with time after being adhered and sufficient weather resistance (for example, Japanese Provisional Patent Publication No. 8-245938).
In another example, a self-adhesive elastomer sheet is proposed, which comprises a polymer composition having an epoxidized diene-base block copolymer and a hydrogenated diene-base block copolymer. But residual air problem when the sheet is adhered remains unsolved (for example, Japanese Provisional Patent Publication No. 8-81616).
A recent widespread use of, for example, TV sets with liquid crystal display, TV sets with plasma display panel (PDP), personal computers, mobile-phones, electronic notepads, etc., is accompanied by a requirement for developing a surface protection film that efficiently protects surfaces thereof to be protected (display screens). Such surface protection film needs to have, for example, such transparency that enables visual recognition of the screen. Adhesiveness (such as adhesive force and workability at the time of adhering) to the surface to be protected and a resistance to environmental causes (for example, scratching or peeling) are also required.
Studies on barrier layers which block or cut off an electromagnetic wave or heat ray leaking from a housing of various electric equipments, have been carried out. In the case of display screens of such as TV sets, personal computers, mobile-phones, etc., antireflective (reflection-reducing), antistatic anticlouding, antibacterial and deodorizing functions are needed besides the electromagnetic wave blocking property. For example, in the case of antireflective, a means of forming of a thin layer of λ/4 by sputtering of metal or metal oxide is known (Japanese Provisional Patent Publication No. 2003-524197).
In addition, another means is proposed in which a film comprising an adhesive layer and a substrate layer, and having a advertising logo and/or advertising picture thereon, is adhered to a surface of a front glass etc. of various shops, but in such cases, some parts of adhesive layer tends to remain on the surface to be adhered, when peeled off in the case where the layout of the film is changed. Accordingly, wiping out or cleaning of the remaining adhesives is necessary, taking a lot of time and also resulting in lowering in tackiness necessary for re-adhering and resulting in difficulty in applying the film repeatedly to the surface to be adhered.
Furthermore, the surface to be adhered is generally flat, but especially in the case which the surfaces is unevenness, air tends to be trapped in the space between the surface to be adhered and adhesive layer of the film being adhered, resulting in unevenness of the surface of adhered the film and bringing about deterioration in its appearance, durability, etc. In addition, to improve workability, a film capable of being adhered speedily (with good air expelling ability) has also been desired.
As mentioned above, providing such films is desired, that can be easily and repeatedly adhered to and peeled off from a surface be adhered, and that is excellent in appearance and in durability, even which the product to be adhered is made of various materials such as plastics, metals, fibers, glasses, etc. and has a surface of various configuration such as flat, curved, uneven, etc.